交换链表的节点

发表于


链表节点要这么画成图2这样的不要简单的画图1表示了。
代码如下

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
class Solution {
public:
    ListNode * swapPairs(ListNode* head) {
        auto p = head;
        //no node
        if (p == NULL) { return p; }

        //swap first two nodes
        if (p&&p->next) {
            auto next = p->next;
            p->next = p->next->next;
            next->next = p;
            head = next;//change head node
        }
        //only one node
        else {
            return p;
        }

        //swap rest nodes;
        auto prev = head->next;
        p = head->next->next;
        while (p&&p->next){
            auto next = p->next;
            p->next = p->next->next;
            next->next = p;
            prev->next = next;
            prev = p;
            p = p->next;
        }
        return head;
    }
};